If your goal is simply to have the casual user have a view-only mode, and a link you can share that gives that, this can be accomplished by editing the final portion of the URL from e.g.
Note that, of course, this doesn't stop even a slightly savvy user from changing it back to
/edit, and obtaining whatever permissions that URL would otherwise have granted to them.
This gives a simpler UI (no menus or account selection or the like), with no capacity to do anything but viewing, without changing the URL. If/when that's what you want (disabling edits by default, without truly restricting access), it works great. (At least it did for me, as of the time of this posting.)